Method of preparing an olefin polymerization catalyst



United rates Patent 3,038,864 METHUD 0F BREYARING AN OLEFIN PULYIVTERIZATEON CATALYST Gaetano F. DAlelio, South Bend, Ind., assignor, by direct and mesne assignments, to Dal Mon Research Co., Cleveland, Ohio, a corporation of Delaware No Drawing. Filed Nov. 5, 1957, Ser. No. 694,509 4 Claims. (Cl. 252-441) The present invention is directed to polymerizing an olefin such as ethylene, propylene, butylene, styrene, butadiene, isoprene and the like in an inert solvent in the presence of a catalyst prepared by grinding under inert conditions. a mixture consisting essentially of zirconium metal and ZrCI It is known to prepare a catalyst for the polymerization of ethylene by ball milling together a mixture of Al and TiCl followed by heating the results at 200 C. for 18 hours, thereby giving a product comprising essentially TiCl This procedure is disclosed in French Patent 1,132,506 to Bayer (Example 9). This same patent also discloses ball milling all or part of the product obtained by heating Al powder and TiCl at high temperatures to give a catalyst that will polymerize ethylene. (See Examples 6 and 11 of the patent.) The product that is ball-milled in Example 6 issaid to be TiCl Ti, and Al, possibly with some TiCl The product that is ball-milled in Example 11 is apparently a mixture of Ti, Al, T101 TiCl and AlCl It is also known that a catalyst for the polymerization of ethylene may be prepared at high temperatures by heating mixtures of a1 and ZrCl or Ti and ZrCl or ZrCl, and Na; and ZrCl TiCl and Al.

My invention differs from the Bayer technique in that I have discovered that the product obtained by grinding together Zr and ZrCl alone can be used directly as an olefin-polymerization catalyst, without a heating step in the catalyst preparation.

The following examples illustrate Without limiting the invention.

Example 1 Five grams of granulated Zr sponge and 3.6 grams ZrCl are ball-milled together under pure dry nitrogen for 48 hours in a conventional stainless steel ball mill of 4 ounce capacity, which was about /2 full of /2 inch stainless steel balls. Two grams of the resulting catalyst are suspended in 50 ml. toluene in a 200 ml. stainless steel rocking autoclave. The transfer from the mill to the autoclave is made in a dry box under a slight pressure of nitrogen to avoid contamination with moisture and oxygen. (The catalyst is pyrophoric and is extremely sensitive to such contaminants, and therefore should be handled at all times under inert conditions.) After the catalyst is transferred to the autoclave, the autoclave is sealed and pressured with ethylene to about 500 p.s.i., and heated at a temperature of about l 30 C. for 24 hours. The autoclave is repressured with ethylene from time to time to maintain the pressure at about 500 psi. After the run is completed, the autoclave is cooled, vented, opened, and the crude polyethylene product recovered. The yield is about 45 g. Substitution for the ethylene in Example 1 by propylene, butene-l, pentene-l, hexene-l, styrene, paramethylstyrene, vinyl cyclohexene and the like olefins containing a terminal CH CH grouping produces the corresponding polymers whereas mixtures of such olefins produce copolymers. The catalysts of this invention may be used in conjunction with alkyl metals such as butyllithium, cyclohexyllithium etc., to produce cis polymers of isoprene.

The reaction product, if desired, may be purified by boiling in methanol containing hydrogen chloride, by techniques well-known to those skilled in the art.

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The catalyst as above prepared is useful in polymerizing ethylene at temperatures ranging from about room temperature up to about 200 C., and even higher, and at pressures ranging from a few atmospheres, for example 50 psi, to pressures as high as 10,000 p.s.i., and even higher. For practical operation, however, temperatures in the range of 50200 C., and pressures of 200- 1000 psi. are suitable.

The polymerization reaction is suitably carried out in an inert solvent. Hydrocarbon solvents free from contaminants (especially free from oxygen and oxygen-containing compounds) are preferred. Among the suitable solvents are pentane, hexane, heptane, cyclohexane, octune, benzene, xylene, toluene, and the like.

The amount of activated catalyst is not critical. Relatively small amounts are operable to form relatively large amounts of polymer. In general, a practical range is 0.001 to 1 g. of catalyst per gram of ethylene polymerized. Even larger amounts are operable, but not necessary.

In conducting the ball milling operation it is often convcnient to carry it out in the we way. For example, a hydrocarbon may be added to the mixture to be ball milled, preferably one that will not interfere with the subsequent polymerization reaction. Solvents suitable for use in the polymerization reaction as above described are in general suitable for wet ball milling. The use of such a hydrocarbon in the ball-milling step provides a slurry of the catalyst in an inert medium which is easily handled. It the mixture is ground in the dry way, this should be done under an inert atmosphere such as pure dry nitrogen or a noble gas. The resultant milled mixture is extremely pyrophoric and should be handled under an inert atmosphere. If desired the milling can be carried out under an inert atmosphere of nitrogen or the like, and then the milled mixture can be flushed from the mill with an inert hydrocarbon. Similarly, the milling can be carried out partly in an inert atmosphere and then an inert hydrocarbon can be added to the mill toward the end of the milling in order to slurry the product for ease of handling.

Any grinding or milling whatever of a mixture consisting essentially of Zr and ZrCl will provide a catalyst of some activity. Preferably, however, the milling or grinding should be conducted for at least several hours, and suitably for at least several days. The ZrzZrCl weight ratio can vary considerably, e.g., over the range of lZrzlOOZrCl to l00ZrzlZrCl The polymerization reaction can be carried out for residence times in the range of 2-48 hours. Generally, the reaction will be found to be substantially complete within l024 hours.

The polyole-fins and the polyethylene obtained by practice of this invention can be used in any conventional manner now being used by polyolefins formed by prior art procedures. Such uses include film, molding, pipe, tubing, filament, extruded articles and the like.

I claim:

1. The method of preparing a catalyst suitable for the polymerization of olefins which comprises the step of grinding at room temperature and at ambient temperatures a mixture consisting essentially of Zr metal with ZrCl under inert conditions, said ZrCl starting material being initially substantially inactive as a polymerization catalyst.

2. The method according to claim 1 in which the mixture is ground in an inert hydrocarbon.

3. The method according to claim 1 in which the mixture is ground under nitrogen.

4. The method of preparing a pyrophoric catalyst which comprises the step of ballmilling at room temperature and at ambient temperatures a mixture consisting essentially 3 4 of Zr metal with ZrCl under inert conditions, said ZrCl FOREIGN PATENTS starting material being initially substantially inactive as 533 362 Belgium May 16 1955 Polymerizafim Catalyst 1,132,506 France Nov. 5, 1956 References Cited in the file of this patent 5 OTHER REFERENCES UNITED STATES PATENTS Treatise on Inorganic and Theoretical Chemistry, by 2,703,794 Roedel Mar. 8, 1955 Mellor, vol. VII, page 143, Longmans and Co., New York, 2,827,447 Nowlin et a1 Mar. 18, 1958 19 2,893,984 Seelbach et a1 July 7, 1959 Polyethylene, by Raff et a1., Interscience Pub. Co., 2,899,416 Schreyer et a1 Aug. 11, 1959 10 New York, 1956, pages 80 and 81 pertinent.

2,925,392 Seelbach et a1. Feb. 16, 1960 

1. THE METHOD OF PREPARING A CATALYST SUITABLE FOR THE POLYMERIZATION OF OLEFINS WHICH COMPRISES THE STEP OF GRINDING AT ROOM TEMPERATURE AND AT AMBIENT TEMPERATURES A MIXTURE CONSISTING ESSENTIALLY OF ZR METAL WITH ZRCL2 UNDER INERT CONDITIONS, SAID ZRCL2 STARTING MATERIAL BEING INITIALLY SUBSTANTIALLY INACTIVE AS A POLYMERIZATION CATALYST. 